US2004166864A1PendingUtilityA1
Minimising signal interference within a wireless network
Priority: Mar 28, 2001Filed: Mar 28, 2002Published: Aug 26, 2004
Est. expiryMar 28, 2021(expired)· nominal 20-yr term from priority
H04W 36/00837H04W 84/18H04W 84/10
39
PatentIndex Score
0
Cited by
0
References
0
Claims
Abstract
A wireless telecommunications network ( 100 ) comprises a multiplicity of Bluetooth™ units, some of which are fixed and act as base units (BS 1 ; BS 2 ; BS 3 ; BS 4 ) and some mobile (MS 1 ; MS 2 ; MS 3 ; MS 4 ). The fixed units are connected to a Local Area Network (LAN) along with a telephony gateway ( 4 ) and a PABX ( 5 ) and PSTN ( 6 ). Methods for minimising signal interference as mobile units roam within the network are discussed.
Claims
exact text as granted — not AI-modifiedThe claims defining the invention are as follows:
1 . A method for minimising signal interference within a wireless network comprising a plurality of fixed terminals in wireless communication with one or more mobile terminals roaming within the network, communication links between the fixed and mobile terminals, the method including the steps of generating an integer linear programming problem of the form:
Min
∑
j
∈
L
(
M
p
j
-
∑
i
∈
B
a
i
j
x
i
j
)
(
1
)
such that:
∑
i
∈
B
x
i
j
=
1
,
j
∈
L
(
2
)
∑
j
∈
L
x
i
j
≤
q
i
,
i
∈
B
(
3
)
x
i
j
≤
z
i
j
(
4
)
∑
i
∈
B
z
i
j
≤
I
level
+
p
j
,
j
∈
L
(
5
)
p
j
≤
I
threshold
,
j
∈
L
(
6
)
where
L
=
the
set
of
mobile
terminals
B
=
the
set
of
fixed
terminals
z
i
j
=
{
1
,
if
the
signal
of
fixed
terminal
i
is
received
by
mobile
j
0
,
else
x
i
j
=
{
1
,
if
fixed
terminal
i
connects
with
mobile
j
0
,
else
q
i
=
the
capacity
of
fixed
terminal
i
a
i
j
=
expected
signal
quality
if
mobile
terminal
j
connects
with
fixed
terminal
i
I
level
=
preferred
maximum
number
of
signals
from
fixed
terminals
overlapping
any
mobile
terminal
location
I
threshold
=
maximum
extra
number
of
extra
fixed
terminal
signals
allowed
above
I
level
,
that
can
overlap
a
mobile
terminal
location
before
service
is
inoperable
p
j
=
a
non
-
negative
penalty
variable
solving the above relaxed problem (1) to (3); determining if the solution satisfies constraints (4) to (6), and, if the solution does satisfy these constraints, using the solution to determine the communication links between the fixed and mobile terminals.
2 . The method as claimed in claim 1 , wherein the relaxed problem is solved by: creating a first bipartite graph with the set of fixed and mobile terminals;
applying weightings to the edges of the first bipartite graph to create a weighted bipartite graph; solving an optimal assignment problem for the weighted bipartite graph to derive a second graph having a second set of edges to determine a new set of connections between mobile and fixed terminals.
3 . A method as claimed in claim 2 , wherein the optimal assignment problem can be solved using a Kuhn-Munkres algorithm.
4 . A method as claimed in any of claims 1 to 3 , wherein, if constraints (4) to (6) are not satisfied, then the method includes the further step of applying an iterative heuristic.
5 . A method as claimed in claim 4 , wherein the iterative heuristic is a restricted tree search technique is used.
6 . A method as claimed in claim 5 , wherein the restricted tree search technique may be a limited discrepancy search.
7 . A method as claimed in claim 4 , wherein the iterative heuristic includes firstly reducing signal coverage for a particular fixed terminal while maintaining communication links.
8 . A method as claimed in claim 7 , wherein the iterative heuristic may further include considering whether any one mobile station should be in communication with another fixed terminal instead of the one with which it is presently in communication with.
9 . A wireless network located within a network environment and comprising a plurality of fixed terminals in communication with one or more mobile terminals roaming within the network, the network including control means operable to solve an integer linear programming problem of the form:
Min
∑
j
∈
L
(
M
p
j
-
∑
i
∈
B
a
i
j
x
i
j
)
(
1
)
such that:
∑
i
∈
B
x
i
j
=
1
,
j
∈
L
(
2
)
∑
j
∈
L
x
i
j
≤
q
i
,
i
∈
B
(
3
)
x
i
j
≤
z
i
j
(
4
)
∑
i
∈
B
z
i
j
≤
I
level
+
p
j
,
j
∈
L
(
5
)
p
j
≤
I
threshold
,
j
∈
L
(
6
)
where
L
=
the
set
of
mobile
terminals
B
=
the
set
of
fixed
terminals
z
i
j
=
{
1
,
if
the
signal
of
fixed
terminal
i
is
received
by
mobile
j
0
,
else
x
i
j
=
{
1
,
if
fixed
terminal
i
connects
with
mobile
j
0
,
else
q
i
=
the
capacity
of
fixed
terminal
i
a
i
j
=
expected
signal
quality
if
mobile
terminal
j
connects
with
fixed
terminal
i
I
level
=
preferred
maximum
number
of
signals
from
fixed
terminals
overlapping
any
mobile
terminal
location
I
threshold
=
maximum
extra
number
of
extra
fixed
terminal
signals
allowed
above
I
level
,
that
can
overlap
a
mobile
terminal
location
before
service
is
inoperable
p
j
=
a
non
-
negative
penalty
variable
by solving the above relaxed problem (1) to (3); and to determine if the solution satisfies constraints (4) to (6), and, if the solution does satisfy these constraints, using the solution to determine the communication links between the fixed and mobile terminals.
10 . A network as claimed in claim 10 , wherein the control means is operable to solve the relaxed problem by:
creating a first bipartite graph with the set of fixed and mobile terminals; applying weightings to the edges of the first bipartite graph to create a weighted bipartite graph; and solving an optimal assignment problem for the weighted bipartite graph to derive a second graph having a second set of edges, to determine a new set of connections between mobile and fixed terminals.
11 . A network as claimed in claim 10 , wherein the optimal assignment problem is solved using a Kuhn-Munkres algorithm.
12 . A network as claimed in any one of claims 9 to 11 , wherein, if constraints (4) to (6) are not satisfied, then the control means is further operable to apply an iterative heuristic.
13 . A network as claimed in claim 12 , wherein the iterative heuristic is a restricted tree search technique.
14 . A network as claimed in claim 13 , wherein the restricted tree search technique is a limited discrepancy search.
15 . A network as claimed in claim 12 , wherein the iterative heuristic includes firstly reducing signal coverage for a particular fixed terminal while maintaining communication links.
16 . A network as claimed in claim 15 , wherein the iterative heuristic further includes the step of considering whether any one mobile station should be in communication with another fixed terminal instead of the one with which it is presently in communication with.Join the waitlist — get patent alerts
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